How to decide what programming language to use for Startup

We have now got to the stage that we have qualified Drag (Kanban in email) as a concept, have validated 3,400 early access requests and now we’re ready for go for it. This means we need to make decisions about what programming language to build our product on, what architecture and how we can be efficient. To give some context I am not technical, however, I do operate some small SaaS businesses so have solid experience in decision-making on technology stacks. Here are some answers.